I always think that Hemingway is my favorite character when reflecting on the film, but from recent viewings I find Brody's over-the-top turn as Dali! and Gad as Detective Tisserant to be inexhaustible founts of delight! Top marks of course go to the soundtrack and score (which maybe serve better than any other elements of the film to drive home our universal nostalgia for eras long past.)
Allen definitely hits the nail on the head in his theme of the universalized "Golden Age Syndrome," and has to get top marks for not devolving into the cynicism that the plot so easily could been steeped in (especially considering the fate many of Gil's heroes and heroines faced.)
This might be the best reflection of Allen's existentialist motifs and outlook, and a good compliment to his potentially harder to digest films. That Allen chose to opt for more sweet than bitter in his conclusion, maybe reflects something optimistic for all of us hoping to make the most of the times we are in.